Apple's mobile phone hacked my friend and accidentally set up junk iMessage messages. How can I get back to normal?

Click Settings-Information-Blacklist-Cancel the number of friends.

Specific operation steps:

1, open the phone and click "Settings";

2. Enter the settings and go down to "Information";

3. Click on the information to find the "blacklist";

4. Click to enter the blacklist, and the blacked-out mobile phone number will be displayed;

5. Click on the phone number to be restored, and the word "Unlocked" will appear;

6. Click Unblock to finish.